1. Field of the Invention
The present invention relates to sprinkler assemblies for corrosive environments, more specifically, to a shroud that covers the sprinkler head element of the sprinkler assembly in order to protect the element from the corrosive gases and vapors in the environment and that can post a notification when the shroud needs to be replaced.
2. The Prior Art
Industrial plants generate unwanted and undesirable byproducts, including noxious, flammable, and corrosive vapors and gases. These vapors and gases must be removed from the premises, preferably at the rate that they are generated. Ductworks, known as scrubber ducts, operating at negative pressures are designed to do so. Since these scrubber ducts frequently carry vapors and gases which are pyrophoric and highly volatile, they are required to be outfitted with sprinklers. The heat-sensitive head of a sprinkler assembly operating in such a corrosive environment must be protected from the gases and vapors of that environment. In the sprinkler heads of the prior art, such as that shown in U.S. Pat. No. 4,964,470, issued to Gaulin on Oct. 23, 1990 and entitled SPRINKLER CONNECT TO SCRUBBER DUCT, a shroud in the shape of a bag surrounds the sprinkler head to protect it from the environment. The nature of the shroud is such that it melts at a temperature that is higher than the normal temperature of the environment but lower than the operating temperature of the sprinkler head so that the sprinkler head is exposed for operation.
The shrouds, which are typically composed of polyethylene or polypropylene, are somewhat sensitive to the corrosive gases. As a result, they eventually break down, leaving the sprinkler head exposed to the corrosive effects of the gases. Thus, in order to maintain a properly operating sprinkler system, the shrouds must be visually inspected periodically and replaced when they are no longer able to protect the sprinkler head. For example, in the typical semiconductor fabrication facility, the average shroud is effective for about one year. In order to maintain a reasonable margin of safety, these sprinkler heads are inspected twice a year. However, certain sprinklers are exposed to much higher concentrations of corrosive gases than the average and, in extreme cases, only last for about a week. Obviously, these sprinklers must be inspected much more often.
In the case of the sprinkler heads of the Gaulin patent, each sprinkler head must be manually removed from the scrubber duct for inspection or, in the case of other sprinkler systems, the entire scrubber duct system must be shut down to manually inspect the sprinkler heads. Such periodic inspections are costly in terms of time and labor and, if the scrubber duct system must be shut down, costly in terms of lost production. Thus, there is an ongoing need for an alternative to periodic visual inspections of each sprinkler head of the system so that the costs associated with maintaining the proper operation of these sprinkler systems is minimized.